Process for producing flame resistant organic textiles

ABSTRACT

CELLULOSIC AND OTHER TEXTILES ARE RENDERED FLAME RESISTANT UPON TREATMENT WITH SINGLE-BATH AQUEOUS SOLUTIONS CONTAINING TETRAKIS(HYDROXMETHYL)PHOSPHONIUM CHLORIDEOR THE RELATED TETRAKIS(HYDROXYMETHYL)PHOSPHONIUM HYDROXIDE, TRIS(HYDROXYMETHYL)PHSOPHINE, AND TRIS(HYDROXYMETHYL)PHOSPHINE OXIDE-AND CYANAMIDE, IN MOLE RATIOS OF ABOUT FROM 1:0.5 TO 1:4, RESPECTIVELY, AND CATALYZED PREFERABLY BY A PHOSPHORUS-CONTAINING COMPOUND, SUCH AS PHOSPHORIC ACID, AMMONIUM PHOSPHATE, CHLOROMETHYLPHOSPHORIC ACID, AND SODIUM PHOSPHATE. THE SOLUTIONS ARE APPLIED TO VARIOUS FABRICS BY THE PAD-DRY-CURE TECHNIQUE, AND THE TREATMENTS ARE FOUND TO BE DURABLE TO INNUMERABLE LAUNDERING CYCLES. THE FINISH CONTAINED THE ADDED QUALITY OF WRINKLE RESISTANCE.

, 3,698,854 Patented Oct. 17, 1972 3,698,854 PROCESS FOR PRODUCING FLAME RESISTANT ORGANIC TEXTILES Darrell J. Donaldson, Floyd L. Normand, and George L. Drake, .Ir., Metairie, La., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed June 24, 1970, Ser. No. 49,556 Int. Cl. D06m 13/32, 13/38 US. Cl. 8116 P 6 Claims ABSTRACT OF THE DISCLOSURE Cellulosic and other textiles are rendered flame resistant upon treatment with single-bath aqueous solutions containing tetrakis(hydroxymethyl)phosphonium chlorideor the related tetrakis(hydroxymethyl)phosphonium hydroxide, tris(hydroxymethyl)phosphine, and tris(hydroxymethyl)phosphine oxideand cyanamide, in mole ratios of about from 1:05 to 1:4, respectively, and catalyzed preferably by a phosphorus-containing compound, such as phosphoric acid, ammonium phosphate, chloromethylphosphonic acid, and sodium phosphate. The solutions are applied to various fabrics by the pad-dry-cure technique, and the treatments are found to be durable to innumerable laundering cycles. The finish contained the added quality of wrinkle resistance.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to a process for rendering textiles flame resistant. More specifically, this invention relates to a process for rendering cellulosic and other organic textiles flame resistant upon treatment with one of several solutions containing a phosphorus compound and cyanamidethe phosphorus compound being tetrakis(hydroxymethyDphosphonium chloride (THPC) or a derivative related thereto-and a catalyst of the phosphoric acid type. Textile products treated by the process of the instant invention are durable to repeated launderings and continue to be flame resistant. The treated products are obviously useful in the home, oflice, dormitory, etc. in the form of drapes, sheets, upholstery, garments, etc.

The main object of the instant invention is to provide a new method of rendering textiles flame resistant.

Another object of the instant invention is to cause cyanamide to react with phosphorus compounds of the type THPC by utilizing an acidic catalyst, such as phosphoric acid, to produce a flame resistant finish which is durable to innumerable launderings, and has the added property of wrinkle resistance without yellowing the textile material.

Tetrakis(hydroxymethyl)phosphonium c h l o r i d e is known to react with nitrogen compounds such as amines to form polymeric materials which, when applied to organic textiles, renders them flame resistant (see US. Patents 2,809,941 and 2,812,311). However, when THPC was reacted with cyanamide a slightly soluble material was formed and the fabric, treated with this material did not pass the vertical flame test.

OBrien reported on a cyanamide-phosphoric acid flame retardant fiinsh for cotton. In the treating bath it was necessary to use at least 20% phosphoric acid to achieve any degree of flame resistance. The finish was not durable to laundering, and failed the standard vertical flame test after about 10 laundering cycles [see Textile Research J., 38, page 256 (1968)]. We discovered that by incorporating THPC in the above formulation and an acid in catalytic concentration an insoluble polymeric material is formed and the fabric passes the standard vertical flame test (US. Federal Supply Service Textile Test Methods, Federal Specification CCC-T-l9l6, Method 5902, US. Government Printing Ofiice, 1951). For example, a cotton fabric padded With a solution containing about 20.8% THPC and 9.2% cyanamide failed to pass the standard vertical flame test. However, when 1% of an acidic substance, such as phosphoric acid was added to the above solution, the fabric passed the test.

In general terms, the invention is this. A solution is prepared containing THPC and cyanamide in about 1:0.5 to about 1:4 mole ratio the preferred ratio range being from 1:2 to 1:3 THPC to cyanamide. To this solution an acidic substance such as phosphoric acid is added to give about from 0.5% to about 4% concentration, the preferred concentration being in the range of 1.5% to 2.5%. The organic fibrous material is immersed in this solution and the excess liquid removed by conventional textile methods. The material is then dried and cured by any conventional manner such as an oven. It is of advantage to dry the textile at a temperature of about from 50 to C. for about from 1 to 10 minutes, before it is cured at a temperature of about from 110 C. to C. for about from 1 to 10 minutes.

The fabric can also be dried and cured in a single step at the temperature range of about from 110 to 180 C.; however, the strength of the fabric is decreased as compared to the conventionally dry-cured samples.

Th degree of flameprofing imparted to a textile by these compounds can be varied from a low degree to a very high degree by varying the amount of polymer deposited on the fabric surface. Surface active agents, water repellents, resin and other textile treating agents may be incorporated in the treating bath.

Other advantages in accordance with the spirit of the instant invention are that textiles treated by this process are shrink resistant, Wrinkle resistant, glow resistant, and rot resistant, and these effects are permanent and resistant to laundering and dry cleaning.

In this process the term organic fibrous material includes any hydrophilic fibrous material that is a material which absorbs or adsorbs water, such as cotton, rayon, ramie, jute, wool, paper, cardboard, and the like materials and combinations of these as well as any chemical and physical modifications of these.

In reference to the chemical reagents, the phosphorus containing compounds related to the preferred THPC, such as products formed from its decomposition and derivatives thereof can be used. For example, the intermediate THPOH can be used, as well as the oxide and other phosphonium salts. The THPOH is generally not a compound which is retrieved from the top of the counter and poured. In fact, THPOH can be obtained by adding an aqueous solution of NaOH to THPC, enough to give a pH of about from 7 to 8.

Illustrative examples of suitable nitrogen compounds include amides, and particularly cyanamide. Acidic materials compatible with this invention are phosphoric acid, ammonium and metal salts of persulfate, sulfamate, phosphate, chloride, nitrate, sulfate, and the like organic acids, such as acetic, citric and substituted phosphoric .acids.

The treated samples of the instant invention were tested in various manners, among which was the standard vertical flame test (AATCC Test Method 34-1966), the angle flame test use by Guthrie et al. (see Textile Research J. 23, pages 527-62, 1953), wrinkle resistance (AATCC Test Method 66-1968), and rot resistance (AATCC Test Method 30-1957T).

The following examples are provided to illustrate the significant details of the invention and should not be construed as limiting the invention in any manner whatever. The percent figures cited throughout the examples are based on weights.

Example 1 Scoured, desized, and bleached cotton sateen was impregnated with an aqueous solution containing 10.2 g. of cyanamide, 23.3 g. of THPC (a THPC to cyanamide mole ratio of 1:2), 2.5 g. of phosphoric acid catalyst (H 'PO and 64 g. of water, to a 70% wet pickup. This sample was dried minutes at 85 C. and cured 5 minutes at 150 C. in an electric oven. The sample was rinsed with hot water for about 15 minutes and then allowed to dry. The finished sample had a 17% add-on, and was submitted to and passed the 180 angle match test. The sample was further submitted to 30 laundering cycles, using a commercial detergent, then tested again, and found to pass the 180 angle match test as before, thereby illustrating the durability of the treatment to laundering.

Example 2 A fabric sample of the type employed in Example 1 was impregnated with an aqueous solution containing 10.7 g. of cyanamide, 24.4 g. of THPC (a THPC to cyanamide mole ratio of 1:2), 1.0 g. of H PO and 63.9 g. of water to a wet pickup of 70%. The fabric was dried 5 minutes at 85 C. and cured 5 minutes at 150 C. in an electric oven. The finished sample had a 12% add-on, and had excellent flame resistance, as measured by standard vertical flame test. This flame resistance was equally effective after the sample had been submitted to 30 laundering cycles. Therefore, add-ons as low as 12% imparted durable flame resistance to the textile.

Example 3 A fabric sample of the type employed in Example 1 was impregnated with an aqueous solution containing 16.3 g. THPC, 7.2 g. cyanamide (a THPC to cyanamide mole ratio of 1:2), 1.6 g. of H PO and 74.9 g. of water to a wet pickup of 70%. The fabric was dried 5 minutes at 85 C. and cured minutes at 140 C. in an electric oven. The sample was rinsed with hot water for 15 minutes and then allowed to dry. The finished sample had an 8.4% add-on, 1.73% phosphorus, and the flame test gave a 4.0 in. char length. The sample was submitted to 30 laundering cycles, and had a 1.38% phosphorus content with 3.75 in. char length.

Example 4 A fabric sample of the type employed in Example 1 was impregnated with an aqueous solution containing g. THPC, 13.8 g. cyanamide (a THPC to cyanamide mole ratio of 1:3), 2.5 g. H PO and 63.7 g. of water to a wet pickup of 70%. The sample was dried 5 minutes at 85 C. and cured 3 minutes at 160 C. in an electric oven, then hotwater-washed and dried. The add-on was 16.3%, and the sample passed the standard vertical flame test after 30 laundering cycles with a 2.5 inch char length. Therefore, a ratio of 1:3 of THPC-cyanamide imparted durable flame resistance to the cotton textile.

Example 5 A fabric sample of the type employed in Example 1 was impregnated with an aqueous solution containing 27 g. THPC, 5.9 g. cyanamide (a THPC to cyanamide mole ratio of 1:1), 2.5 g. of H PO catalyst, and 64.6 g. of water to a 70% wet pickup. The fabric was dried at 85 C. for 5 minutes and cured at 160 C. for 3 minutes. After washing and drying, the fabric sample had a 14.7% addon, and after 30 laundering cycles the flame test yielded a 3.0 in. char length. Therefore, a THPC to cyanamide mole ratio of 1:1 also provided flame ISiStance to the cotton te ti e.

Example 6 The fabric sample and treatment was as in Example 5 except that the THPC to cyanamide mole ratio was 1:2. The finished fabric sample had a 9% add-on and after submitting the sample to 30 laundering cycles the flame test yielded a 3.0 inch char length.

Example 7 A fabric sample of the type employed in Example 1 was impregnated with an aqueous solution containing 22.2% THPC, 9.8% cyanamide, 4.0% dibasic sodium phosphate (Na HPO and 64% water to a wet pickup of about The fabric sample was dried 4 minutes at C. and cured 3 minutes at 160 C., then washed and dried as the other fabric samples. The add-on Was 18.4%, and after 30 launderings passed the standard vertical flame test with a 4.0 char length. Therefore dibasic sodium phosphate was an elfective catalyst in the THPC-cyanamide reaction.

Example 8 A desized, scoured, and bleached cotton printcloth was impregnated with a solution containing 19.5 g. THPC, 8.6 g. of cyanamide (a THPC to cyanamide mole ratio of 1:2), 2.0 g. H PO and 69.9 g. of water to give about wet pickup. The wet impregnated fabric was dried 5 minutes at 85 C. and cured 5 minutes at 150 C., then washed in hot water and allowed to dry. The sample thus treated had a 19.9% add-on and a 2.6% phosphorus content. The flame test showed an initial char length of 3.75 inches after 30 laundering cycles. After laundering the phosphorus content was 2.22%. A portion of the treated fabric was placed in a soil burial bed. The treated sample retained 70% of its original breaking strength after 6 weeks in the burial bed while the untreated control had degraded completely within the first week of burial. Therefore, the THPC-cyanamide-H PO system not only imparts durable flame retardancy to the textile but also protects the material from attack by microorganisms.

EXAMPLE 9 A fabric sample of the type employed in Example 8 was impregnated with an aqueous solution containing 19.5 g. THPC, 8.6 g. cyanamide (a THPC to cyanamide mole ratio of 1:2), 2.0 g. of H PO and 69.9 g. of water to a wet pickup of 85%. The sample was dried 2 minutes at 85 C. and cured 2% minutes at 150 C. on a tenter frame. The fabric was Washed and dried as in the other examples, and had a 15.4% add-on. After the sample was submitted to 30 laundering cycles the flame test gave a 5.0 inch char length. This fabric was submitted to wrinkle recovery evaluation tests and gave a dry, conditioned value of 253. The wet crease recovery angle was 226. Therefore, the data shows that the finish imparts wrinkle recovery properties to the textile.

EXAMPLE 10 A fabric sample of the type employed in Example 8 was impregnated with an aqueous solution containing 17.3 g. THPC, 7.7 g. of cyanamide (a THPC to cyanamide mole ratio of 1:2), 5 g. of ammonium phosphate (NH HPO and 70 g. water to a wet pickup of 70%. The fabric was dried 5 minutes at 85 C. and cured 5 minutes at C., then given a hot water wash and dried as in the other examples. The add-on was 17.5%. After 10 launderings the char length was 3.5 inches. The THPC-cyanamide finished is applicable to light weight fabrics such as printcloth.

EXAMPLE 1 1 Desized, scoured, and bleached twill was impregnated with an aqueous solution containing 19.5 g. THPC, 8.6 g. of cyanamide (a THPC to cyanamide mole ratio of 1:2), 2.0 g. of chloromethyl phosphonic acid catalyst, and 699 g. of water to a wet pick p of about 60%. The

fabric sample was dried at 85 C. for 3 minutes and cured 3 minutes at 160 C., then hot water washed and dried as in the other examples. The add-n was 12%. The sample was submitted to 30 laundering cycles, then flame tested as the others. The char length was 3.75 inches. Therefore, chloromethylphosphonic acid was also an effective catalyst for the THPC-cyanamide system.

EXAMPLE 12 A wool fabric sample was impregnated with an aqueous solution containing 15.7 g. of THPC, 10.3 of cyanamide (a THPC to cyanamide ratio of 1:3), 4.0 g. of H PO catalyst, and 70 g. of water to about 80% wet pickup. The fabric sample was dried at 85 C. for 5 minutes and cured at 150 C. for 5 minutes, then washed in hot water for 15 minutes. The add-on was 15%, and the fabric passed the 180 angle match test.

EXAMPLE 13 Cellulosic cardboard was impregnated with an aqueous solution containing 15.7 g. THPC, 10.3 g. cyanamide (a THPC to cyanamide mole ratio of 1:3), 4.0 g. of H PO catalyst, and 70 g. water to a wet pickup of about 110%. The sample was dried minutes at 85 C. and cured 5 minutes at 150 C. The sample was washed in hot water for minutes and allowed to dry. The add-on was 28%. The sample was submitted to a 180 angle match test and passed.

EXAMPLE 14 A broadcloth sample, a blend of 50% cotton and 50% avril, was impregnated with an aqueous solution containing 19.5% g. of THPC, 8.6 g. of cyanamide (a THPC to cyanamide mole ratio of 1:2), 2.0 g. of H PO catalyst, and 69.9 g. of water to a wet pickup of 62% After drying the sample 5 minutes at 85 C. and curing 5 minutes at 150 C. the sample was washed and dried as the other fabric samples. The add-on was 10%. The sample was then submitted to a 180 angle flame test and passed.

We claim:

1. A process for imparting flame resistance to a cellulosic material, comprising:

(a) impregnating the cellulosic material with an aqueous solution containing (I) a phosphorus compound selected from the group consisting of tetrakis (hydroxymethyl)phosphonium chloride, tetrakis(hydroxymethyl) phosphonium hydroxide, tris(hydroxymethyl)phosphine oxide, and tris(hydroxymethyl) phosphine, (II) cyanamide, said phosphorus compound and cyanamide being present in a phosphorus compound to cyanamide molar ratio of about from 1:05 to 1:4, and (III) about from 0.5% to 4.0% of chloromethylphosphonic acid;

(b) drying the wet-impregnated material at a temperature of about from C. to C. for about from 1 to 10 minutes;

(0) curing the dry, impregnated material at a temperature of about from 110 C. to C. for about from 1 to 10 minutes; and

.(d) water-washing the cured material to remove all unreacted reagents.

2. The process of claim 1 wherein the phosphorus compound is tetrakis(hydroxymethy1)phosphonium chloride.

3. The process of claim 1 wherein the phosphorus compound is tetrakis(hydroxymethyl)phosphonium hydroxide.

4. The process of claim 1 wherein the phosphorus compound is tris (hydroxymethyDphosphine oxide.

5. The process of claim 1 wherein the phosphorus compound is tris (hydroxymethyl)phosphine.

6. The product produced by the process of claim 1.

US. Cl. X.R.

8116.2, 120, 127.6, 128; 106-15 F P; 117-137; 252- 8.1; 260-219, DIG. 24 

